In the conventional art, an air conditioner that comprises a heat source unit, a utilization unit, and a connection piping, which connects the heat source unit and the utilization unit, is known. When this air conditioner is constructed, a procedure is performed onsite wherein a refrigerant circuit of the air conditioner is filled with a refrigerant.
Nevertheless, if the refrigerant circuit is filled with an amount of refrigerant that is not appropriate, then there is a risk that the functions of the air conditioner will decline. Consequently, there is a need to determine whether the refrigerant circuit is filled with an appropriate amount of refrigerant.
Accordingly, among air conditioners that comprise a receiver, the interior of which can pool the refrigerant inside the refrigerant circuit, there exists an air conditioner that is provided with a liquid surface detecting means, which detects the liquid surface of the refrigerant pooled inside the receiver. With regard to this air conditioner, a refrigerant amount determining operation that determines the amount of refrigerant that has been filled in the refrigerant circuit by performing control that maintains the liquid surface inside the receiver at a constant level has been proposed (refer to Japanese Patent Application Publication No. 2006-292212).